Docker demo repository isn't stated correctly in README

expected: `sorintlab/sirclesdemo`
actual: `alectolytic/sirclesdemo`

EDIT:
The actual repo was created because the original one was missing:
From https://hub.docker.com/r/alectolytic/sirclesdemo/:

```
A demo container based on upstream demo. Created as the official one was unavailable.

https://github.com/sorintlab/sircles#quick-start-using-docker
```
Any ideas why?